Sex allocation in animals

Eg, Leigh; Ea, Herre; Ea, Fischer

doi:10.1007/bf01952069

Cited by 33 publications

(23 citation statements)

References 54 publications

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“…The sex ratio did not deviate significantly from 1:1, in accordance with optimal resource allocation in populations with random mating (Leigh et al 1985, Mari et al 2008. Nevertheless, skewed sex ratios have been reported for some octocorals (Brazeau & Lasker 1990), specifi- Table 2.…”

Section: Discussionsupporting

confidence: 67%

Sexual structure of a highly reproductive, recovering gorgonian population: quantifying reproductive output

Cupido¹,

Cocito²,

Manno³

et al. 2012

Mar. Ecol. Prog. Ser.

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A population of the Mediterranean red gorgonian Paramuricea clavata has exhibited unexpected resilience after being impacted by 2 anomalous mortality events in 1999 and 2003. To understand the recovery mechanisms, we examined the population reproductive structure and reproductive output based on data collected via non-destructive sampling techniques. The overall population sex ratio was balanced, though the spatial distribution of sexes was significantly segregated. Dividing the population into 14 size classes on the basis of their measured average annual growth revealed a decreasing monotonic trend of abundance of larger classes. The Recruitment class was consistently dominant. The minimum size at first reproduction was 8.5 cm in height, corresponding to an age of ~3 yr. The percentage of fertile colonies increased with size, reaching 90% in size Class 9. Polyp fecundity increased with colony size and did not differ signif- icantly between healthy and damaged colonies. As the number of mature oocytes produced by a colony is a function of polyp fecundity and of the number of reproductive polyps, colony reproduc- tive output increased exponentially with size. The population reproductive output (145 × 103 mature oocytes m−2 yr−1) was one-fifth of that measured in stable, undamaged populations and came mainly from the medium size classes. After the catastrophic mortality, the population has been recovering, albeit with reduced reproductive output. Moreover, it has exhibited a 2-fold increase in recruitment rate, 3-fold greater than that measured in other, undisturbed populations. Our findings are consistent with a strict density-dependent recruitment control operating in crowded, stable P. clavata populations

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Section: Discussionsupporting

confidence: 67%

Sexual structure of a highly reproductive, recovering gorgonian population: quantifying reproductive output

Cupido¹,

Cocito²,

Manno³

et al. 2012

Mar. Ecol. Prog. Ser.

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“…There is considerable clear evidence for intragenomic conflict over sex allocation (Hamilton, 1967;Werren and Beukeboom, 1998) -indeed, sex ratio distorting elements provide some of the clearest examples of 'selfish genes' that distort the sex ratio in order to maximize their own transmission, but to the determent of the fitness of the individual carrying them (eg, Werren et al, 1981). As Leigh (Leigh et al, 1985;Leigh, 1986) suggested, a chromosomal sex ratio distorting mechanism might be vulnerable to invasion by selfish genetic elements, in which case suppression of the mechanism by autosomal genes would be favoured. Part of the variation between species in the extent to which they adjust the sex ratio might simply represent stochastic variation in whether they had been subject to invasion by selfish genetic elements followed by autosomal suppression.…”

Section: Sex Determination Adaptation and Constraint In Sex Allocationmentioning

confidence: 99%

“…Indeed, in some areas the fit of data to theoretical predictions can be expected to be so close that sex ratio theory has been argued to have a predictive power almost comparable to that of the 'hard' sciences of chemistry and physics (Hamilton, 1996). This has allowed work on the sex ratio to (a) provide some of the best quantitative evidence for the relative importance of natural Heredity selection at the gene, individual, kin and population levels (Leigh et al, 1985;Beukeboom and Werren, 1992;Seger and Stubblefield, 1996;Chapuisat and Keller, 1999;West et al, 2000a), and (b) to address very general questions about the precision of adaptation and the limits on natural selection (Herre, 1987;West and Herre, 1998;Herre et al, 2001). In addition, reasoning has been reversed and observed sex ratios have been used to estimate parameters upon which the sex ratio is predicted to depend, but which can be difficult to measure directly (eg, the inbreeding rate in malaria parasites, which is a parameter of clinical importance (Read et al, 1992;West et al, 2000bWest et al, , 2001a, the factor limiting reproduction in parasitic wasps (West and Rivero, 2000), or the relatedness between competing male fig wasps (West et al, 2001b)).…”

Section: Introductionmentioning

confidence: 99%

Sex ratios

2002

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“…Theory is very clear concerning the conditions under which a sex-changer can invade a population consisting of pure males and females: if the sex-changer produces and fertilises more eggs than a pure female produces or a pure male fertilises, then a mutant for sex-changing will spread in the population Leigh et al, 1976;Charnov, 1982;Leigh et al, 1985). This, however, is a trivial statement, only saying that when sex-changers are more fit than gonochores, they will replace the latter.…”

Section: Introductionmentioning

confidence: 99%

To change or not to change sex: A comparison between twoOphryotrocha species (Polychaeta)

Berglund

1991

Evol Ecol

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SummaryThe polychaete Ophryotrocha puerilis is a male-to-female sex-changer, whereas O. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in some O. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that in O. puerilis males should not benefit reproductively from a size increase as much as males in O. labronica: hence O. puerilis but not O. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundity per se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. In O. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas in O. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained in O. puerilis, and why separate sexes are maintained in O. labronica.

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Sex allocation in animals

Cited by 33 publications

References 54 publications

Sexual structure of a highly reproductive, recovering gorgonian population: quantifying reproductive output

Sexual structure of a highly reproductive, recovering gorgonian population: quantifying reproductive output

Sex ratios

To change or not to change sex: A comparison between twoOphryotrocha species (Polychaeta)

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